CODEWITHSUNDEEP
design-patterns
Marty Wallace
Marty Wallace

Reputation: 35734

Simple Factory - how to improve this

class MyConcreteFactory
{
    public static function create($model, $typeId)
    {
        if ($typeId == 'customer') {
            return new CustomerWrapper($model);
        }
        if ($typeId == 'order') {
            return new OrderWrapper($model);
        }
        if ($typeId == 'product') {
            return new ProductWrapper($model);
        }
    }
}

How can i improve this? The main flaw is that managing the typeId checking logic will need changed every time a new entity type is introduced or changed.

Upvotes: 0

Views: 34

Answers (3)

recursive
recursive

Reputation: 86064

It depends on the facilities provided by the language you're using. One approach is to read the string to type mapping out of a configuration file.

class MyConcreteFactory
{
    private Map(string, constructor) KnownTypes = ReadFromConfig();

    public static function create($model, $typeId)
    {
        var constructor = KnownTypes($typeId);
        var result = constructor($model);
        return result;
    }
}

Upvotes: 2

gurghet
gurghet

Reputation: 7707

Depends very much on the context. If you just want a wrapper just pass an object that extends a wrappable interface and wrap it.

public interface Wrappable { public Wrapped wrap() }

public class Factory {
    static WrappedObj create(Wrappable model) {
        return model.wrap();
     }
}

Upvotes: 0

Alex
Alex

Reputation: 382

In java you can improve your pattern with help of the Reflection API. 

public class Example {
    public static Object create(Class c) {
        try {
            //Creating a new instance with the default constructor of that Class
            return c.newInstance();
        } catch (Exception e) {e.printStackTrace();}
        return null;
    }
    public static void main(String[] args) {
        //For example: Instantiating a HashMap 
        HashMap hashMap = (HashMap) create(HashMap.class);
    }
}

Useful link

Upvotes: 0

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